Waste paper has for many years been recycled and utilized as a source of feedstock for the manufacture of paper products. The availability of recycled paper, however, is subject to the economics of the recovery, sorting and cleaning of the waste paper from the waste paper containing materials. The recovery, sorting and cleaning of waste paper for recycling has, therefore, had such implications as requiring voluntary sorting of the paper at the source of generation, which requires special handling by the generator; dedicated pickup of specially segregated materials by a recycler; and component separation by the recycler after collection.
Waste plastics have become increasingly important because of their very long term resistance to degradation and decomposition in the environment and because of the hazardous nature of the gaseous compounds that are produced when plastics are incinerated. Recycling of these plastics has begun, but only slowly and only certain plastics are specifically separated from the waste stream. Because of the increasing problem of waste plastics, it is being considered that plastic packaging be limited or even banned. The recovery, sorting and cleaning of waste plastics for recycling has therefore, as with waste paper, had such implications as requiring voluntary sorting of the plastic at the source of generation and dedicated pickup of specific plastics by a recycler to be viable as a source of plastic to be utilized by the plastics industry.
It has long been recognized that the achieving of a method of separating waste paper and plastics from the extraneous contaminating components that typically accompany a paper containing waste material would be highly desirable. This is particularly true if the paper and plastic containing waste material is municipal solid waste. Municipal solid waste typically contains 40-60% paper materials along with a varying assortment of glass, metals, rags, food wastes, plastics, etc.
More specifically, I have found typical component compositions for municipal solid wastes to be as follows:
TABLE 1 ______________________________________ Paper 50.0% Iron 8.0% Aluminum 2.0% Plastic 6.0% Glass 8.0% Food Waste 1.5% Grass Clippings 2.5% Moisture 20.0% Miscellaneous 2.0% (Leather, Textiles, Rubber, Wood, etc.) 100.0% ______________________________________
Currently the vast majority of paper and plastic containing waste materials are being landfilled, resulting in the loss of paper and recyclable materials and the using up of valuable land space. Landfills also threaten the environment with contamination of surface waters and groundwaters, and present health hazards and public nuisances by increasing numbers of disease-carrying birds, rodents and insects.
The problem is an ever-increasing one. By their existence, municipalities and industries generate paper-containing and plastic-containing wastes continually and these wastes must be properly disposed of. Various approaches such as incineration, composting and producing refuse-derived fuel have been considered as alternative solutions to sanitary landfills.
Incineration, although it can reduce the amount of landfilling required, produces undesirable and hazardous pollutants which are released to the air, primarily by the combustion of plastics contained in the waste materials and the volatilizing of metals such as aluminum also contained therein. Incineration also produces few products to generate revenue except for energy sales of steam and electricity, which are dependent on adjacent customers and subject to rates set by local public utilities, and thus the burden of debt retirement of an incineration facility falls upon the public.
Composting, which is the process of subjecting waste materials to microbial action to produce a soil-like material has potential only as a soil conditioner. Because it contains little nutrient value, compost cannot compete as a fertilizer, and quite unfortunately, the concentration of heavy metals resulting from the compost may cause unacceptable levels of heavy metals to be absorbed into plants, and therefore into the food chain.
Producing refuse-derived fuel from waste materials requires that a series of steps be taken to separate combustible materials from non-combustible materials. This results in several classification processes, producing a number of low quality products of limited value. The refuse-derived fuel produced contains plastics and as such, when combusted, will produce undesirable and hazardous pollutants, which are released to the atmosphere.
Because of the problems that are inherent to the present methods of waste disposal, because of the continuing need to dispose of waste materials, and because of the need to recover valuable products that are now being lost, it has become highly appropriate for the perfection of the instant separation and recovery of component fractions from waste paper and plastic containing materials.